Heat exchanger, air-conditioning apparatus equipped with heat exchanger, and method for producing heat exchanger

ABSTRACT

A heat exchanger includes plural heat exchanger cores, each of which includes plural tabular fins with notches formed therein and plural heat transfer tubes. The plural fins are disposed such that planes of the fins face each other. The plural heat transfer tubes are hairpin tubes each of which is bent in a U-shape. The hairpin tubes are placed in the notches in the fins so as to extend in a direction crossing the planes of the fins. The plural heat exchanger cores are placed side by side in a direction crossing the direction of the notches in the fins and at the same time a direction along the planes of the fins. A brazing sheet is disposed between adjacent ones of the heat exchanger cores. The adjacent ones of the heat exchanger cores are brazed together by the brazing sheet.

TECHNICAL FIELD

The present invention relates to a heat exchanger adapted to exchangeheat between refrigerant and air, an air-conditioning apparatus equippedwith the heat exchanger, and a method for producing the heat exchanger.

BACKGROUND ART

Hitherto, a finned-tube heat exchanger having heat transfer tubes andfins is known as a heat exchanger for an air-conditioning apparatus.Types of heat transfer tube include a circular tube whosecross-sectional shape is circular and a flat tube whose cross-sectionalshape is a chamfered rectangle. Hereinafter, the heat exchanger using acircular tube will be referred to as a circular-tube heat exchanger andthe heat exchanger using a flat tube will be referred to as a flat-tubeheat exchanger.

As a method for producing a flat-tube heat exchanger, a method is knownin which U-shaped notches extending in a widthwise direction of finsfrom one end of the fins are formed and a flat tube is press-fitted intothe notches. On the other hand, a circular-tube heat exchanger isproduced by forming circular holes in the fins and inserting a circulartube into the holes. In such a circular-tube heat exchanger, heatexchanger cores are not placed side by side in an up-down direction. Onthe other hand, a flat-tube heat exchanger is known in which plural heatexchanger cores are placed side by side in the up-down direction asdescribed, for example, in Patent Literature 1.

CITATION LIST Patent Literature

-   Patent Literature 1: Japanese Patent No. 5980424

SUMMARY OF INVENTION Technical Problem

Generally, in the flat-tube heat exchanger in which plural heatexchanger cores are placed side by side in the up-down direction, theadjacent heat exchanger cores are coupled together by a couplingelement. Therefore, if a load is exerted on the flat-tube heatexchanger, there is concern that relative locations of the heatexchanger cores may be shifted due to falling of the coupling element ordisplacement between the coupling element and the heat exchanger.

The present invention has been made to solve the above problem and anobject thereof is to provide a heat exchanger that keeps relativelocations of heat exchanger cores from shifting, an air-conditioningapparatus equipped with the heat exchanger, and a method for producingthe heat exchanger.

Solution to Problem

According to one embodiment of the present invention, there is provideda heat exchanger comprising a plurality of heat exchanger cores, each ofthe plurality of heat exchanger cores including a plurality of tabularfins with notches formed therein and a plurality of heat transfer tubes,wherein: the fins are disposed such that planes of the fins face eachother and the heat transfer tubes are placed in the notches in the finsso as to extend in a direction crossing the planes of the fins; and theplurality of heat exchanger cores are placed side by side in a directioncrossing the notches and extending along the planes of the fins, andadjacent ones of the heat exchanger cores are joined together.

Also, according to another embodiment of the present invention, there isprovided a method for producing a heat exchanger that comprises aplurality of heat exchanger cores, each of the plurality of heatexchanger cores including a plurality of tabular fins with notchesformed therein and a plurality of heat transfer tubes, the methodcomprising: forming the heat exchanger cores in which the fins aredisposed such that planes of the fins face each other and that the heattransfer tubes are placed in the notches in the fins so as to extend ina direction crossing the planes of the fins; placing the plurality ofheat exchanger cores side by side in a direction crossing a direction ofthe notches and extending along the planes of the fins; and joiningtogether adjacent ones of the heat exchanger cores.

Advantageous Effects of Invention

In the heat exchanger according to one embodiment of the presentinvention, the plurality of heat exchanger cores are placed side by sidein a direction crossing a direction of the notches formed in the finsand extending along the planes of the fins, and adjacent ones of theheat exchanger cores are joined together. This keeps relative locationsof the adjacent heat exchanger cores from shifting.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1(a) and 1(b) are perspective views of an outdoor unit on which aflat-tube heat exchanger according to Embodiment 1 of the presentinvention is mounted.

FIG. 2 is a diagram showing a related art flat-tube heat exchangermounted on an outdoor unit of an air-conditioning apparatus.

FIGS. 3(a) and 3(b) are diagrams showing the flat-tube heat exchangeraccording to Embodiment 1.

FIGS. 4(a) and 4(b) are sectional views of the flat-tube heat exchangeraccording to Embodiment 1.

FIGS. 5(a) to 5(e) are enlarged views of part D in FIG. 4(b).

FIGS. 6(a) and 6(b) are sectional views of a flat-tube heat exchangeraccording to Embodiment 2 of the present invention.

FIGS. 7(a) to 7(e) are enlarged views of part F in FIG. 6(b).

FIGS. 8(a) to 8(c) are sectional views of a flat-tube heat exchangeraccording to Embodiment 3 of the present invention.

FIGS. 9(a) to 9(c) are sectional views of a flat-tube heat exchangeraccording to Embodiment 4 of the present invention.

FIGS. 10(a) and 10(b) are sectional views of a flat-tube heat exchangeraccording to Embodiment 5 of the present invention before being loadedinto an electric furnace.

FIGS. 11(a) and 11(b) are sectional views of a flat-tube heat exchangeraccording to Embodiment 6 of the present invention.

FIG. 12 is a diagram showing a flat-tube heat exchanger according toEmbodiment 7 of the present invention.

FIGS. 13(a) and 13(b) are sectional views of the flat-tube heatexchanger according to Embodiment 7 of the present invention.

FIGS. 14(a) and 14(b) are diagrams showing a flat-tube heat exchangeraccording to Embodiment 8 of the present invention.

FIG. 15 is a diagram showing a flat-tube heat exchanger according toEmbodiment 9 of the present invention.

FIG. 16 is a diagram showing one step in production of a heat exchangercore.

FIG. 17 is a diagram showing one step in production of the flat-tubeheat exchanger.

FIG. 18 is a diagram showing one step in production of the flat-tubeheat exchanger.

DESCRIPTION OF EMBODIMENTS

Embodiments of a heat exchanger according to the present invention willbe described in detail below with reference to the drawings. Note thatthe present invention is not limited by the embodiments described below.Also, in the following drawings, some components are not shown in theiractual size relationships.

Embodiment 1

FIGS. 1(a) and 1(b) are perspective views of an outdoor unit on which aflat-tube heat exchanger according to Embodiment 1 of the presentinvention is mounted. FIG. 1(a) is a perspective view of the entireoutdoor unit 200 and FIG. 1(b) is a perspective view showing the outdoorunit 200 from which some elements have been removed. Note that in FIGS.1(a) and 1(b), an X direction corresponds to a front-rear direction ofthe outdoor unit 200, a Y direction corresponds to a left-rightdirection of the outdoor unit 200, and a Z direction corresponds to anup-down direction of the outdoor unit 200. The outdoor unit 200 has avertically long outer shell as a whole. The outdoor unit 200 includes anupper front panel 51, a lower front panel 52, a left side panel 53, anda fan guard 54. Besides, the outdoor unit 200 also includes a back panellocated on the back side, being opposite to the upper front panel 51 andlower front panel 52 as well as a right side panel located on the rightside, being opposed to the left side panel 53. The back panel and theright side panel are located at positions not illustrated in FIG. 1. Theupper front panel 51 and the lower front panel 52 make up front part ofthe outer shell of the outdoor unit 200. The left side panel 53 makes upleft part of the outer shell of the outdoor unit 200. The right sidepanel makes up right part of the outer shell of the outdoor unit 200.The back panel makes up back part of the outer shell of the outdoor unit200. The fan guard 54 is provided above the outdoor unit 200.

An air inlet 59 is formed in the left side panel 53. Air inlets similarto the air inlet 59 are formed also in the back panel and the right sidepanel. An air outlet 55 is formed in the fan guard 54.

As shown in FIG. 1(b), the outdoor unit 200 includes a base panel 56disposed at the bottom. The base panel 56 makes up a bottom part of theouter shell of the outdoor unit 200. A flat-tube heat exchanger 101, acompressor 57, and an accumulator 58 are disposed on the base panel 56.The flat-tube heat exchanger 101, compressor 57, and accumulator 58 arefixed to the base panel 56, for example, by screwing.

The flat-tube heat exchanger 101 is disposed such that it faces the leftside panel 53, the back panel, and the right side panel. That is, theflat-tube heat exchanger 101 is U-shaped in cross section in a planeparallel to the X direction and the Y direction. The flat-tube heatexchanger 101 is fixed to the left side panel 53 as well as to the basepanel 56 as described above. Refrigerant is supplied to the flat-tubeheat exchanger 101. Also, air taken in through the air inlets in therear panel and the right side panel as well as through the air inlet 59passes through the flat-tube heat exchanger 101. The flat-tube heatexchanger 101 exchanges heat between the refrigerant and passing air.During cooling operation of an air-conditioning apparatus connected withthe outdoor unit 200, the flat-tube heat exchanger 101 functions as acondenser, i.e., as a radiator, and thereby condenses and liquefies therefrigerant. Also, during heating operation of the air-conditioningapparatus connected with the outdoor unit 200, the flat-tube heatexchanger 101 functions as an evaporator, and thereby evaporates orvaporizes the refrigerant.

The compressor 57 compresses and discharges refrigerant. The compressor57 is connected to a suction side of the accumulator 58. The accumulator58 serves to accumulate liquid refrigerant. The compressor 57 isconnected to a discharge side to the flat-tube heat exchanger 101 duringcooling operation of the air-conditioning apparatus connected with theoutdoor unit 200 and is connected to a use side heat exchanger mountedon a non-illustrated indoor unit, during heating operation of theair-conditioning apparatus.

Also, a non-illustrated fan is mounted on the outdoor unit 200 and isused to take air into the outdoor unit 200 and discharge air out of theoutdoor unit 200. The fan is disposed on top of the outdoor unit 200 andis surrounded and covered by the fan guard 54. As the fan rotates, airis taken into the outdoor unit 200 through the air inlets in the rearpanel and the right side panel as well as through the air inlet 59 whileair in the outdoor unit 200 is released out of the outdoor unit 200through the air outlet 55.

FIGS. 3(a) and 3(b) are diagrams showing the flat-tube heat exchangeraccording to Embodiment 1. FIG. 3(a) is a general view of the flat-tubeheat exchanger 101 before being bent into a U-shape. FIG. 3(b) is anenlarged view of part B in FIG. 3(a), i.e., hairpin-like bent portion offlat tubes of the flat-tube heat exchanger 101. The flat-tube heatexchanger 101 includes two heat exchanger cores 11 and 12. Each of theheat exchanger cores 11 and 12 includes hairpin tubes 1, which areU-bent flat heat transfer tubes, and plural fins. The plural fins aredisposed in parallel such that planes of each pair of adjacent fins faceeach other. In FIG. 3, the plural fins are illustrated as a fin assembly3. Of the plural fins, a U-shaped notch is formed along a widthwisedirection of each fin in one of a pair of lateral edges extending in alengthwise direction. The hairpin tubes 1 are press-fitted into theU-shaped notches in the plural fins. U-bent portions of the hairpintubes 1 are located in one of end portions of each heat exchanger core11 or 12. The end portions of the hairpin tubes 1 that are located atanother end of each heat exchanger core 11 or 12, are cut sections thatallow cross-sectional shape of the flat-tubes to be checked visually.The cut sections of the hairpin tubes 1 are connected withnon-illustrated joints used to connect flat tubes and circular tubeswith each other, a header 5, and a distributor 6.

In the following description, a stage direction means a directioncrossing a direction of the notches in the fins and at the same time adirection extending along the planes of the fins. That is, the stagedirection is an up-down direction of the flat-tube heat exchanger 101and corresponds to the Z direction in FIG. 1.

The two heat exchanger cores 11 and 12 are placed side by side in thestage direction. In other words, the two heat exchanger cores 11 and 12are placed side by side along the up-down direction. The heat exchangercores 11 and 12 are joined together by a brazing sheet 7. The heatexchanger cores 11 and 12 abut against each other in the stage directionand loaded into an electric furnace with a brazing sheet 7 insertedtherebetween, thereby being brazed to each other.

According to Embodiment 1, the heat exchanger cores 11 and 12 are placedside by side in the stage direction and joined together using a brazingsheet 7. Thus, even if a load is exerted on the flat-tube heat exchanger101, relative positional locations of the heat exchanger cores 11 and 12can be prevented from shifting.

Also, since it is sufficient that the two heat exchanger cores 11 and 12are abut against each other and loaded into an electric furnace with abrazing sheet 7 inserted therebetween, the flat-tube heat exchanger 101is easy to assemble during production. Also, production time andproduction cost of the flat-tube heat exchanger 101 can be curbed.

Now, effects of the heat exchanger according to Embodiment 1 will bedescribed in comparison with an existing heat exchanger.

FIG. 2 is a diagram showing an existing flat-tube heat exchanger mountedon an outdoor unit of an air-conditioning apparatus. In FIG. 2,components similar to those of the flat-tube heat exchanger 101 ofEmbodiment 1 described with reference to FIG. 3 are denoted by the samereference numerals as the corresponding components in FIG. 3, anddescription thereof will be omitted. The existing flat-tube heatexchanger 100 includes heat exchanger cores 111 and 10. Each of the heatexchanger cores 111 and 10 includes fin assemblies 3. The heat exchangercores 111 and 10 are coupled together and fixed by coupling elements 4placed at intervals in a direction crossing planes of fins in the finassemblies 3. The coupling elements 4 are fitted around hairpin tubes 1and this configuration fixes the heat exchanger cores 111 and 10 to eachother. In some cases, the coupling elements 4 are fixed to the hairpintubes 1 with an adhesive.

In the existing flat-tube heat exchanger 100 of FIG. 2, the couplingelements 4 coupling together the heat exchanger cores 111 and 10 areplaced at intervals in the direction crossing the planes of fins in thefin assemblies 3. Thus, fins cannot be placed in locations where thecoupling elements 4 are placed. That is, in the direction in which thehairpin tubes 1 extend by passing through fins, fins do not exist insome part. In contrast, according to Embodiment 1, since the two heatexchanger cores 11 and 12 are placed side by side in the stagedirection, fins can be placed anywhere in the direction in which thehairpin tubes 1 extend by passing through fins. In this way, Embodiment1 allows a larger number of fins to be placed as compared with theexisting example. This ensures high heat exchange characteristics of theflat-tube heat exchanger 101.

FIGS. 4(a) and 4(b) are sectional views of the flat-tube heat exchangeraccording to Embodiment 1. FIG. 4(a) is a sectional view of theflat-tube heat exchanger along line A-A in FIG. 3(a) and FIG. 4(b) is asectional view along line C-C in FIG. 4(a). The lateral direction inFIGS. 4(a) and 4(b) coincides with the stage direction in the figures.As shown in FIG. 4(b), the end faces of fins 211 of the heat exchangercore 11 that face the heat exchanger core 12 are not bent, and the endfaces of fins 212 of the heat exchanger core 12 that face the heatexchanger core 11 are not bent. Besides, a brazing sheet 7 is insertedbetween the heat exchanger cores 11 and 12 as described above. That is,the brazing sheet 7 is interposed between the unbent end faces of thefins.

Now, combinations of materials for the fins 2, hairpin tubes 1, andbrazing sheet 7 according to Embodiment 1 will be described. A firstcombination uses a bare material for the fins 2, uses a clad tube forthe hairpin tubes 1, and does not use a brazing material for brazingbetween the fins 2 and the hairpin tubes 1. A second combination uses aclad material for the fins 2, uses a bare tube for the hairpin tubes 1,and does not supply a brazing material for brazing between the fins 2and hairpin tubes 1. A third combination, which uses preplaced brazing,uses a bare material for the fins 2, uses a bare tube for the hairpintubes 1, and supplies a brazing material for brazing between the fins 2and the hairpin tubes 1. Here, the bare material is a material made upof a core and the clad material is a material made by bonding together acore and a brazing material. The bare tube is a flat tube without abrazing material provided on a surface and the clad tube is a flat tubehaving a brazing material layer on its surface.

The first combination uses a clad tube for the hairpin tubes 1, i.e.,for the flat tubes. The use of the clad tube for the hairpin tubes 1makes it possible to use a bare material that does not need a brazingmaterial layer, for the fins 2. An aluminum brazing material containsSi, i.e., silicon. Because Si has very high hardness, there is a concernthat wear on an edge of a cutting blade of a metal die used in formingthe fins 2 may be accelerated. The use of a bare material that does notneed a brazing material for the fins 2 can reduce the wear on the edgeof the cutting blade.

The second combination uses a clad material for the fins 2. The use of aclad material for the fins 2 makes it possible to use a bare materialmade up of only a core for the hairpin tubes 1, thus leading toreduction in cost.

The third combination uses bare materials for the fins 2 and the hairpintubes 1 and uses preplaced filler metal. The preplaced filler metal is abrazing material set near brazing points before being loaded into anelectric furnace to supply the brazing material to between workpieces tobe brazed during brazing. Preplaced filler metal makes it easy to adjustand change the amount of the brazing material and the use of preplacedfiller metal exerts the effect of reducing wear on the edge of thecutting blade of the metal die. Thus, the use of preplaced filler metalallows the production cost of the heat exchanger cores 11 and 12 to becurbed.

FIGS. 5(a) to 5(e) are enlarged views of part D in FIG. 4(b). FIG. 5shows the flat-tube heat exchanger at a stage before being loaded intoan electric furnace. FIG. 5(a) is an example in which a bare materialmade up of only a core 2 a is used for the fins 2 and a brazing material7 b is used for the brazing sheet 7. The use of a bare material made upof only the core 2 a for the fins 2 exerts the effect of suppressingwear on the edge of the cutting blade. The use of the brazing material 7b for the brazing sheet 7 improves designability of joins because thebrazing sheet 7 is melted after being loaded into the electric furnace.

FIG. 5(b) is an example in which a clad material made up of the core 2 aand a brazing material 2 b is used for the fins 2 and a brazing materialis used for the brazing sheet 7. Since a clad material made up of thebrazing material 2 b is used for the fins 2, a bare tube can be used forthe hairpin tubes 1. The use of a bare tube allows the production costof the heat exchanger cores 11 and 12 to be curbed. Also, the use of thebrazing sheet 7 improves the designability of joins as in the case ofthe example of FIG. 5(a).

FIG. 5(c) is an example in which a clad material made up of the core 2 aand the brazing material 2 b is used for the fins 2 and a bare materialmade up of only the core 7 a is used for the brazing sheet 7. Bysupplying the brazing material used for brazing between the fins 2 andthe brazing sheet 7 from the brazing material 2 b of the fins 2, a barematerial can be used for the brazing sheet 7. This makes it possible tocurb the cost of the brazing sheet 7. Since a metal junction is formedbetween the fins 2 and the brazing sheet 7 by brazing, the heat transferarea of the fins 2 is increased. This improves heat exchange performanceof the heat exchanger cores 11 and 12.

FIG. 5(d) is an example in which a bare material made up of only thecore 2 a is used for the fins 2 and a clad material made up of the core7 a and the brazing material 7 b formed on a surface of the core 7 a isused for the brazing sheet 7. The use of a bare material for the fins 2exerts the effect of suppressing wear on the edge of the cutting blade.Since a clad material is used for the brazing sheet 7, the core of thebrazing sheet 7 remains after being loaded into the electric furnace,brazing the fins 2 and the brazing sheet 7 to each other and forming ametal junction. This increases the heat transfer area of the fins 2,thereby improving heat exchange performance of heat exchangers of theheat exchanger cores 11 and 12.

FIG. 5(e) is an example in which a clad material made up of the core 2 aand the brazing material 2 b is used for the fins 2 and a clad materialmade up of the core 7 a and the brazing material 7 b formed on thesurface of the core 7 a is used for the brazing sheet 7. The core of thebrazing sheet 7 remains after being loaded into the electric furnace,brazing the fins 2 and the brazing sheet 7 to each other and forming ametal junction. This increases the heat transfer area of the fins 2,thereby improving heat exchange performance of heat exchangers of theheat exchanger cores 11 and 12. Also, a larger amount of the brazingmaterial is supplied to the brazing points, which eliminates the lack ofbrazing material and thereby enabling stable brazing.

Note that although in Embodiment 1, the brazing sheet 7 is joined bybrazing, this is not restrictive. The brazing sheet 7 may be joined withan adhesive. Also, the brazing between the fins 2 and hairpin tubes 1may be performed during brazing between the heat exchanger cores 11 and12 performed using the brazing sheet 7, or in another step before thebrazing between the heat exchanger cores 11 and 12 performed using thebrazing sheet 7. Also, brazing of the header 5 and the distributor 6 maybe performed all at once by loading the header 5 and the distributor 6into the electric furnace at the time of brazing of the heat exchangercores performed using the brazing sheet 7. The header 5 and thedistributor 6 may be brazed in separate steps before and after brazingbetween the heat exchanger cores.

Embodiment 2

FIGS. 6(a) and 6(b) are sectional views of a flat-tube heat exchangeraccording to Embodiment 2 of the present invention. FIG. 6(a) is asectional view of the flat-tube heat exchanger according to Embodiment 2along a line corresponding to line A-A in FIG. 3(a) and FIG. 6(b) is asectional view along line E-E in FIG. 6(a). The lateral direction inFIGS. 6(a) and 6(b) coincides with the stage direction in the figures.

As shown in FIGS. 6(a) and 6(b), heat exchanger cores 112 and 122 areplaced side by side in the stage direction. As shown in FIG. 6(b), thoseend faces of fins 221 of the heat exchanger core 112 that face the heatexchanger core 122 are bent, forming fin collars 8. Similarly, the endfaces of fins 222 of the heat exchanger core 122 that face the heatexchanger core 112 are bent, forming fin collars 8. That is, on the heatexchanger cores 112 and 122 that abut against each other, the end facesof the fins 221 and 222 of the heat exchanger cores 112 and 122 are bentata part where the heat exchanger cores 112 and 222 abut against eachother. A brazing sheet 7 is inserted between the heat exchanger cores112 and 122. That is, the brazing sheet 7 is interposed between the bentend faces of the fins 221 and bent end faces of the fins 222.

According to Embodiment 2, since the brazing sheet 7 is interposedbetween the bent end faces of the fins 221 and 222, a wider contact areacan be secured between the fins 221 and brazing sheet 7 as well asbetween the fins 222 and brazing sheet 7. Thus, the brazing sheet 7 canbe brazed stably to the fins 221 and 222. Also, brazing joint strengthof the brazing sheet 7 with the fins 221 and 222 is increased.

FIGS. 7(a) to 7(e) are enlarged views of part F in FIG. 6(b). FIG. 7shows the flat-tube heat exchanger at a stage before being loaded intoan electric furnace. FIG. 7(a) is an example in which a bare materialmade up of only the core 2 a is used for the fins 221 and 222 and thebrazing material 7 b is used for the brazing sheet 7. The use of a barematerial for the fins 221 and 222 exerts the effect of suppressing wearon the edge of the cutting blade of the metal die. Also, the use of thebrazing material 7 b for the brazing sheet 7 improves designability ofjoins because the brazing sheet 7 is melted after being loaded into theelectric furnace. Furthermore, on the heat exchanger cores 112 and 122,end faces of the fins 221 and 222 of the heat exchanger cores 112 and122 are bent at a part where the heat exchanger cores 112 and 122 abutagainst each other, and the fin collars 8 are formed on the fins 221 and222, thereby exerting the above-mentioned effect.

FIG. 7(b) is an example in which a clad material made up of the core 2 aand brazing material 2 b is used for the fins 221 and 222 and a brazingmaterial is used for the brazing sheet 7. Since a clad material made upof the brazing material 2 b is used for the fins 221 and 222, a baretube can be used for the hairpin tubes 1. The use of a bare tube allowsthe production cost of the heat exchanger cores 112 and 122 to becurbed. Also, the use of the brazing sheet 7 improves the designabilityof joins. Also, a large amount of the brazing material is supplied tothe brazing points, which eliminates the lack of a brazing materialduring joining, and thereby enabling stable brazing.

FIG. 7(c) is an example in which a clad material is used for the fins221 and 222 and a bare material made up of only the core 7 a is used forthe brazing sheet 7. By supplying the brazing material used to braze thebrazing sheet 7 to the fins 221 and 222 from a brazing material layer ofthe fins 221 and 222, a bare material can be used for the brazing sheet7. This makes it possible to curb the cost of the brazing sheet 7. Sincethe brazing sheet 7 is brazed to the fins 221 and 222, forming a metaljunction, the heat transfer area of the fins 221 and 222 is increased,which improves the heat exchange performance of the flat-tube heatexchangers. Furthermore, on the heat exchanger cores 112 and 122, theend faces of the fins 221 and 222 of the heat exchanger cores 112 and122 are bent at a part where the heat exchanger cores 112 and 122 abutagainst each other, and fin collars 8 are formed on the fins 221 and222, thereby exerting the above-mentioned effect.

FIG. 7(d) is an example in which a bare material made up of only thecore 2 a is used for the fins 221 and 222 and a clad material made up ofthe core 7 a and the brazing material 7 b formed on the surface of thecore 7 a is used for the brazing sheet 7. The use of a bare material forthe fins 221 and 222 exerts the effect of suppressing wear on the edgeof the cutting blade of the metal die. Since a clad material is used forthe brazing sheet 7, the core of the brazing sheet 7 remains after beingloaded into the electric furnace, brazing the brazing sheet 7 to thefins 221 and 222 and forming a metal junction. This increases the heattransfer area of the fins 221 and 222, thereby improving the heatexchange performance of the heat exchanger cores 112 and 122.Furthermore, on the heat exchanger cores 112 and 122, the end faces ofthe fins 221 and 222 of the heat exchanger cores 112 and 122 are bent ata part where the heat exchanger cores 112 and 122 abut against eachother, and fin collars 8 are formed on the fins 221 and 222, therebyexerting the above-mentioned effect.

FIG. 7(e) is an example in which a clad material made up of the core 2 aand brazing material 2 b is used for the fins 221 and 222 and a cladmaterial made up of the core 7 a and the brazing material 7 b formed onthe surface of the core 7 a is used for the brazing sheet 7. The core ofthe brazing sheet 7 remains after being loaded into the electricfurnace, brazing the brazing sheet 7 to the fins 221 and 222 and forminga metal junction. This increases the heat transfer area of the fins 221and 222, thereby improving the heat exchange performance of the heatexchanger cores 112 and 122. Also, a larger amount of the brazingmaterial is supplied to the brazing points, which eliminates the lack ofa brazing material and thereby enabling stable brazing. Furthermore, onthe heat exchanger cores 112 and 122, the end faces of the fins 221 and222 of the heat exchanger cores 112 and 122 are bent ata part where theheat exchanger cores 112 and 122 abut against each other, and fincollars 8 are formed on the fins 221 and 222, thereby exerting theabove-mentioned effect.

Embodiment 3

FIGS. 8(a) to 8(c) are sectional views of a flat-tube heat exchangeraccording to Embodiment 3 of the present invention. FIG. 8(a) is asectional view of the flat-tube heat exchanger according to Embodiment 3along a line corresponding to line A-A in FIG. 3(a). That is, FIG. 8(a)shows a section of the flat-tube heat exchanger according to Embodiment3 in the stage direction. FIG. 8(b) is a sectional view along line G-Gin FIG. 8(a). The lateral direction in FIGS. 8(a) and 8(b) coincideswith the stage direction in the figures. FIG. 8(c) is an enlarged viewof part H in FIG. 8(b). FIG. 8(c) shows the flat-tube heat exchanger ata stage before being loaded into an electric furnace. As shown in FIGS.8(a) and 8(b), heat exchanger cores 311 and 312 are placed side by sidein the stage direction. As shown in FIG. 8(c), according to Embodiment3, a clad material made up of the core 2 a and brazing material 2 b isused for the fins 231 of the heat exchanger core 311 and the fins 232 ofthe heat exchanger core 312. No brazing sheet is disposed between theheat exchanger cores 311 and 312. When the two heat exchanger cores 311and 312 are loaded into the electric furnace while abutting against eachother, the brazing material 2 b of the fins 231 and 232, which are madeof a clad material, flows into a gap between the cores 2 a by capillaryaction, thereby forming a brazed joint. Since no brazing sheet isdisposed, the flat-tube heat exchanger is easy to assemble duringproduction, which results in a reduction in production time andproduction cost.

Embodiment 4

FIGS. 9(a) to 9(c) are sectional views of a flat-tube heat exchangeraccording to Embodiment 4 of the present invention. FIG. 9(a) is asectional view of the flat-tube heat exchanger according to Embodiment 4along a line corresponding to line A-A in FIG. 3(a). That is, FIG. 9(a)shows a section of the flat-tube heat exchanger according to Embodiment4 in the stage direction. FIG. 9(b) is a sectional view along line I-Iin FIG. 9(a). The lateral direction in FIGS. 9(a) and 9(b) coincideswith the stage direction in the figures. FIG. 9(c) is an enlarged viewof part J in FIG. 9(b). FIG. 9(c) shows the flat-tube heat exchanger ata stage before being loaded into an electric furnace. As shown in FIG.9(c), the end faces of fins 241 of the heat exchanger core 411 facingthe heat exchanger core 412 are bent, and the end faces of fins 242 ofthe heat exchanger core 412 facing the heat exchanger core 411 are alsobent. That is, on the heat exchanger cores 411 and 412 abutting againsteach other, the fins 241 and fins 242 are bent at a part where the heatexchanger cores 411 and 412 abut against each other. The brazing sheet 7is not disposed between the heat exchanger cores 411 and 412.

When the two heat exchanger cores 411 and 412 are loaded into theelectric furnace while abutting against each other, the brazing material2 b of the fins 241 and 242, which are made of a clad material, flowsinto a gap between the cores 2 a by capillary action, thereby forming abrazed joint. Since no brazing sheet is disposed, the flat-tube heatexchanger is easy to assemble during production, which results inreduced production time and production cost. Furthermore, on the heatexchanger cores 411 and 412, the end faces of the fins 241 and 242 ofthe heat exchanger cores 411 and 412 are bent at a part where the heatexchanger cores 411 and 412 abut against each other, thereby forming fincollars 8. Thus, a wider contact area can be secured between the fins241 of the heat exchanger core 411 and the fins 242 of the heatexchanger core 412. Consequently, the fins 241 and 242 can be brazedstably to each other. Also, brazing joint strength between the fins 241and 242 is increased.

Embodiment 5

FIGS. 10(a) and 10(b) are sectional views of a flat-tube heat exchangeraccording to Embodiment 5 of the present invention before being loadedinto an electric furnace. FIG. 10(a) is a sectional view of theflat-tube heat exchanger according to Embodiment 5 along a linecorresponding to line A-A in FIG. 3(a). That is, FIG. 10(a) shows asection of the flat-tube heat exchanger according to Embodiment 5 in thestage direction. FIG. 10(b) is a sectional view along line K-K in FIG.10(a). The lateral direction in FIGS. 10(a) and 10(b) coincides with thestage direction in the figures. In Embodiment 5, heat exchanger cores511 and 512 are placed side by side in the stage direction. Hairpintubes 1 are exposed on end faces of fins 252 at a part where the heatexchanger core 512 abuts against the heat exchanger core 511. End facesof fins 251 are bent at a part where the heat exchanger core 511 abutsagainst the heat exchanger core 512. A brazing sheet 7 is insertedbetween the heat exchanger cores 511 and 512. The brazing sheet 7 ofEmbodiment 5 is made up of only a brazing material. According toEmbodiment 5, the hairpin tubes 1 of the heat exchanger core 512 and thefins 251 of the heat exchanger core 511 are brazed together. Generally,flat tubes are more rigid and hardly deformed as compared with fins.Thus, brazing according to Embodiment 5 is more stable than when onegroup of fins and another group of fins are brazed to each other.

Embodiment 6

FIGS. 11(a) and 11(b) are sectional views of a flat-tube heat exchangeraccording to Embodiment 6 of the present invention. FIG. 11(a) is asectional view of the flat-tube heat exchanger according to Embodiment 6along a line corresponding to line A-A in FIG. 3(a). That is, FIG. 11(a)shows a section of the flat-tube heat exchanger according to Embodiment6 in the stage direction. FIG. 11(b) is a sectional view along line L-Lin FIG. 11(a). The lateral direction in FIGS. 11(a) and 11(b) coincideswith the stage direction in the figures. In Embodiment 6, heat exchangercores 611 and 612 are placed side by side in the stage direction.Hairpin tubes 1 are exposed on end faces of fins 262 at a part where theheat exchanger core 612 that abuts the heat exchanger core 611. Endfaces of fins 261 are bent ata part where the heat exchanger core 611abuts against the heat exchanger core 612. A clad material made up of acore and brazing material is used for the fins 261 and 262. No brazingsheet is disposed between the heat exchanger cores 611 and 612.According to Embodiment 6, the hairpin tubes 1 of the heat exchangercore 612 and the fins 261 of the heat exchanger core 611 are brazedtogether. Thus, as in the case of Embodiment 5, more stable brazing isensured when one group of fins and another group of fins are brazed toeach other. Also, the use of a clad material for the fins 261 and 262eliminates the need for a brazing sheet, making it possible to reducethe number of parts.

Embodiment 7

FIG. 12 is a diagram showing a flat-tube heat exchanger according toEmbodiment 7 of the present invention. FIG. 12 is a general view of theflat-tube heat exchanger 107 before being bent into a U-shape. FIGS.13(a) and 13(b) are sectional views of the flat-tube heat exchangeraccording to Embodiment 7 of the present invention. FIG. 13(a) is asectional view of the flat-tube heat exchanger according to Embodiment 7along a line corresponding to line M-M in FIG. 12(a). That is, FIG.13(a) shows a section of the flat-tube heat exchanger according toEmbodiment 7 in the stage direction. FIG. 13(b) is a sectional viewalong line N-N in FIG. 13(a). The lateral direction in FIGS. 13(a) and13(b) coincides with the stage direction in the figures. In Embodiment7, heat exchanger cores 711 and 712 are placed side by side in the stagedirection. Hairpin tubes 1 are exposed on end faces of fins 271 at apart where the heat exchanger core 711 of the flat-tube heat exchanger107 abuts against the heat exchanger core 712. Similarly, hairpin tubes1 are exposed on end faces of fins 272 at a part where the heatexchanger core 712 of the flat-tube heat exchanger 107 abuts against theheat exchanger core 711. At least two spacer blocks 9 are disposedbetween the heat exchanger cores 711 and 712. Five spacer blocks 9 aredisposed in the example shown in FIG. 12. The spacer blocks 9 are madeof metal such as aluminum or stainless steel.

When plural spacer blocks 9 are inserted between the heat exchangercores 711 and 712 and loaded into the electric furnace by being placedin contact with hairpin tubes 1 made of a clad tube having a brazingmaterial layer, the heat exchanger cores 711 and 712 are joined togethervia the hairpin tubes 1 and the spacer blocks 9. According to Embodiment7, since the hairpin tubes 1 and the spacer blocks 9, both havingrigidity, are joined together, stable brazing can be achieved andcoupling strength can be increased as well.

Whereas five spacer blocks 9 are disposed in the example shown in FIG.13, this is not restrictive. It is sufficient that two or more spacerblocks 9 are disposed. Note that a brazing material may be suppliedinstead of the clad tube or spacer blocks 9 provided with a brazingmaterial may be used. Also, the joint between the hairpin tubes 1 andthe spacer blocks 9 is not limited to brazing, and an adhesive may beused.

Embodiment 8

FIGS. 14(a) and 14(b) are diagrams showing a flat-tube heat exchangeraccording to Embodiment 8 of the present invention. FIG. 14(a) is ageneral view of the flat-tube heat exchanger 108 before being bent intoa U-shape. FIG. 14(b) is an enlarged view of part O in FIG. 14(a), i.e.,hairpin bends of flat tubes of the flat-tube heat exchanger 108. Theflat-tube heat exchanger 108 includes heat exchanger cores 281 and 282.The heat exchanger cores 281 and 282 are placed side by side in thestage direction. The heat exchanger cores 281 and 282 include pluralfins. The plural fins are disposed in parallel such that the planes ofeach pair of adjacent fins face each other. In FIG. 14, the plural finsare illustrated as a fin assembly 3. Of the plural fins, a U-shapednotch is formed along a widthwise direction of each fin in one of a pairof lateral edges extending in a lengthwise direction. The hairpin tubes1 are press-fitted into the U-shaped notches in the plural fins.According to Embodiment 8, one of the U-bent hairpin tubes 1 is placedso as to bridge between the heat exchanger cores 281 and 282. That is,one of a pair of straight-tube portions of the hairpin tubes extendingin the lateral direction of the flat-tube heat exchanger 108 is placedat a part in the heat exchanger core 281 that is closest to the end facefacing the heat exchanger core 282 while another straight-tube portionis placed at a part in the heat exchanger core 282 that is closest tothe end face facing the heat exchanger core 281. The hairpin tubes 1 areplaced so as to couple together the heat exchanger cores 281 and 282.Besides, a brazing sheet 7 is inserted between the heat exchanger cores281 and 282. The heat exchanger cores 281 and 282 are joined together bythe brazing sheet 7.

When a flat-tube heat exchanger is configured by coupling together twoheat exchanger cores, the join between the two heat exchanger cores islower in strength than other parts. There is a concern that if a load isexerted on the flat-tube heat exchanger, the heat exchanger cores may bedivided along the join. According to Embodiment 8, cut ends of thehairpin tubes 1 are connected with the header 5 and the hairpin sidebridges between the heat exchanger cores 281 and 282. This furtherincreases the strength of the join between the heat exchanger cores 281and 282. Also, there is no need to provide an element configured toincrease the strength of the join. This enables increasing the strengthof the join while curbing increases in the number of parts. In this way,Embodiment 8 makes it possible to facilitate assembly and reduce theproduction cost while increasing the strength of the join between thetwo heat exchanger cores.

Embodiment 9

FIG. 15 is a diagram showing a flat-tube heat exchanger according toEmbodiment 9 of the present invention. FIG. 15 is a general view of theflat-tube heat exchanger 109 before being bent into a U-shape. Theflat-tube heat exchanger 109 includes heat exchanger cores 291 and 292.The heat exchanger cores 291 and 292 are placed side by side in thestage direction. The heat exchanger cores 291 and 292 include pluralfins. The plural fins are disposed in parallel such that the planes ofeach pair of adjacent fins face each other. In FIG. 15, the plural finsare illustrated as a fin assembly 3. Of the plural fins, a U-shapednotch is formed along a widthwise direction of each fin in one of a pairof lateral edges extending in a lengthwise direction. Flat tubes 15 arepress-fitted into the U-shaped notches in the plural fins. According toEmbodiment 9, one of cut ends of each flat tube 15 is connected with aheader 5 and another cut end is also connected with a header 5. That is,both ends of each flat tube 15 are connected with respective headers 5.

As described above, when a flat-tube heat exchanger is configured bycoupling together two heat exchanger cores, the join between the twoheat exchanger cores is lower in strength than other parts. According toEmbodiment 9, since the both ends of the hairpin tubes 1 are connectedwith the respective headers 5, the strength of the join between the heatexchanger cores 291 and 292 can be increased.

Whereas Embodiments 1 to 9 are described above by exemplifying aconfiguration in which two heat exchanger cores are placed side by sidein the stage direction and joined together, this is not restrictive.Three or more heat exchanger cores may be placed side by side in thestage direction, with adjacent heat exchanger cores being joinedtogether.

According to the present invention, since plural heat exchanger coresare placed side by side in the stage direction, although the individualheat exchanger cores are small, a large flat-tube heat exchanger can beconstructed as a whole. By reducing the size of the heat exchangercores, production equipment of the heat exchanger cores can bedownsized, which makes it possible to reduce capital investment. Also,by adjusting the number of heat exchanger cores placed side by side inthe stage direction, flat-tube heat exchangers of various sizes can beproduced easily.

Embodiment 10

Next, a method for producing a flat-tube heat exchanger will bedescribed. As described above, the flat-tube heat exchanger 101 includesthe heat exchanger core 11, the heat exchanger core 12, non-illustratedjoints used to connect flat tubes and circular tubes with each other,the header 5, and the distributor 6. Also, the heat exchanger cores 11and 12 include the hairpin tubes 1 produced by bending flat tubes aswell as include plural fins.

Methods for producing a heat exchanger core include the following. Thefins of heat exchanger cores are cut and created from a metal sheet,such as an aluminum sheet, with high thermal conductivity. The fins arecreated, for example, by press-forming a coiled aluminum sheetcontinuously fed by a progressive die mounted on a high-speed press. Tomake it easier to join fins to flat tubes, each of the fins may beprovided with a fin collar formed by cutting and raising part of a finsurface placed in contact with the flat tubes. The flat tubes are madeof metal, such as aluminum or copper, with high thermal conductivity.The hairpin tubes are created as follows: a flat tube coiled by beingwound around a bobbin is rolled, shaped by being straightened, cut intoa predetermined length, and bent.

The press-formed fins are cut into a predetermined length and stacked.Bent flat tubes or hairpin tubes are press-fitted into the U-shapednotches in the stacked fins to produce the heat exchanger core.

Methods for producing a heat exchanger core include a method differentfrom the above-mentioned press-fitting method as follows. FIG. 16 is adiagram showing one step in production of a heat exchanger coreaccording to Embodiment 10 of the present invention. As shown in FIG.16, fins 2 are cut one by one from a sheet material 20 press-formed bycontinuously feeding a material by a progressive die mounted on ahigh-speed press. Then, plural hairpin tubes 1 are arranged and the fins2 are inserted one by one into the plural hairpin tubes 1 such that thehairpin tubes 1 are placed in the notches in the fins 2. Consequently,the fins 2 are arranged such that the planes of the fins 2 face eachother. Note that rather than the hairpin tubes 1 in which flat tubes arebent, straight, flat tubes may be used without being bent.

Next, the flat tubes, i.e., the hairpin tubes 1, are brazed to the fins2. In the case of the flat-tube heat exchanger according to Embodiment1, the material composition of the fins 2 is as described with referenceto FIGS. 5(a) to 5(e). As with FIGS. 5(b), 5(c), and 5(e), when a cladmaterial made up of the core 2 a and brazing material 2 b is used forthe fins 211 and 212, the hairpin tubes 1 are brazed to the fins 211 and212 by the brazing material 2 b. When a bare material made up of onlythe core 2 a is used for the fins 211 and 212 as with FIGS. 5(a) and5(d) and the hairpin tubes 1 have a brazing material layer, the hairpintubes 1 and fins 2 are brazed together by the brazing material of thehairpin tubes 1. When a bare material made up of only the core 2 a isused for the fins 211 and 212 as with FIGS. 5(a) and 5(d) and thehairpin tubes 1 do not have a brazing material layer, the hairpin tubes1 and the fins 2 are brazed together by being supplied with preplacedfiller metal. The hairpin tubes 1 and the fins 2 are brazed together byfurnace brazing performed in a high-temperature atmosphere furnace.

In the case of the flat-tube heat exchanger according to Embodiment 2,the material composition of the fins 2 is as described with reference toFIGS. 7(a) to 7(e) and a mode of brazing is similar to that of theflat-tube heat exchanger according to Embodiment 1 described above.

FIG. 17 is a diagram showing one step in production of the flat-tubeheat exchanger. Plural heat exchanger cores are created in the mannerdescribed above and placed side by side to assemble a flat-tube heatexchanger. In the example shown in FIG. 17, two heat exchanger cores,namely the heat exchanger cores 11 and 12, are placed side by side.According to Embodiment 10, the heat exchanger cores 11 and 12 areplaced side by side in the stage direction, i.e., in a directioncrossing the direction of the notches in the fins 2 in which the hairpintubes 1 are placed and at the same time in a direction extending alongthe planes of the fins 2. The step of placing the heat exchanger cores11 and 12 side by side may be carried out before the hairpin tubes 1 andfins 2 are brazed together.

After the heat exchanger cores 11 and 12 are placed side by side in thestage direction, the brazing sheet 7 is inserted between the heatexchanger cores 11 and 12 to assemble the flat-tube heat exchanger 101.The assembly of the flat-tube heat exchanger 101 is carried out on awork bench or dolly. In inserting the brazing sheet 7, a jig may be usedto adjust relative locations of the hairpin tubes 1, the fins 2, andbrazing sheet 7 and fix these elements.

After the flat-tube heat exchanger is assembled, parts used to coupletogether cut ends of the hairpin tubes 1 are connected. Examples of thecoupling parts include a U-bend used to connect a pair of heat transfertubes, a header used to connect to individual heat transfer tubes from amain passage, and a distributor. In connecting the cut end of eachhairpin tube 1 to a U-bend, a circular tube, a header, or a distributor,an element called a joint is used in some cases to convert a passagefrom a circular tube to a flat tube.

As the flat-tube heat exchanger 101 assembled in the manner describedabove is loaded into a high-temperature atmosphere furnace, the heatexchanger cores 11 and 12 are brazed together via the brazing sheet 7,thereby creating the flat-tube heat exchanger 101. If the flat-tube heatexchanger 101 is assembled before brazing of the hairpin tubes 1 and thefins 2, the hairpin tubes 1 and the fins 2 are brazed together when theheat exchanger cores 11 and 12 are brazed together.

In the case of the flat-tube heat exchanger according to Embodiment 1,the materials for the brazing sheet 7 are as described with reference toFIGS. 5(a) to 5(e). When the brazing material 7 b is used for thebrazing sheet 7 as with FIGS. 5(a) and 5(b), the brazing sheet 7 ismelted after being loaded into a high-temperature atmosphere furnace,and thus the brazing sheet 7 does not form a single layer in theflat-tube heat exchanger 101. When a bare material made up of only thecore 7 a is used for the brazing sheet 7 as with FIG. 5(c), a brazingmaterial is supplied from the brazing material 2 b of the fins 2 afterbeing loaded into the high-temperature atmosphere furnace. Afterbrazing, the brazing sheet 7 forms a single layer in the flat-tube heatexchanger 101. When a clad material is used for the brazing sheet 7 aswith FIGS. 5(d) and 5(e), the core 7 a remains after being loaded intothe high-temperature atmosphere furnace. Thus, after brazing, thebrazing sheet 7 forms a single layer in the flat-tube heat exchanger101.

In the case of the flat-tube heat exchanger according to Embodiment 2,the material composition of the brazing sheet 7 is as described withreference to FIGS. 7(a) to 7(e) and a mode of the brazing sheet 7 afterbrazing is similar to that of the flat-tube heat exchanger according toEmbodiment 1 described above.

In the case of the flat-tube heat exchanger according to Embodiment 5,the brazing sheet 7 shown in FIG. 10 is made up of only a brazingmaterial. Thus, the brazing sheet 7 is melted after being loaded intothe high-temperature atmosphere furnace, and consequently the brazingsheet 7 does not form a single layer in the flat-tube heat exchanger101.

The hairpin tubes 1 are joined to the U-bends, a header, a distributor,and joints by being loaded into the high-temperature atmosphere furnace.

FIG. 18 is a diagram showing one step in production of the flat-tubeheat exchanger. The flat-tube heat exchanger may be assembled bystacking plural structures each including the heat exchanger core 11,the heat exchanger core 12, and the brazing sheet 7 placed side by sidein the stage direction as shown in FIG. 18. The structures are stackedalong a column direction parallel to the direction of the planes of thefins 2 and crossing the stage direction at right angles.

In a first column, the heat exchanger cores 11 and 12 are placed side byside in the stage direction and the brazing sheet 7 is inserted betweenthe heat exchanger cores 11 and 12. In a second column, similarly theheat exchanger cores 11 and 12 are placed side by side in the stagedirection and the brazing sheet 7 is inserted between the heat exchangercores 11 and 12. This creates a two-column structure. Then, thestructure is loaded into the high-temperature atmosphere furnace. Toprevent the heat exchanger cores in the first column and the heatexchanger cores in the second column from being joined together, ananti-joining sheet 30 for use to prevent joining is inserted between thetwo columns. When the flat-tube heat exchanger is produced by furnacebrazing, carbon fiber is used for the joining prevention sheet, forexample.

In loading the two-column structure into the high-temperature atmospherefurnace, a jig may be used to adjust and fix the relative locations ofthe hairpin tubes 1, the fins 2, and the brazing sheet 7.

Note that the parts used to connect the cut ends of the hairpin tubes 1with each other may be brazed by furnace brazing when the heat exchangercores are brazed together, brazed by burner brazing configured to burn abase material and the brazing material by flames, or brazed byhigh-frequency brazing.

As described above, according to Embodiment 10, production of theflat-tube heat exchanger includes placing the heat exchanger cores 11and 12 side by side in the stage direction, i.e., a direction crossingthe direction of the notches in the fins and at the same time adirection extending along the planes of the fins; and joining togetherthe heat exchanger cores placed side by side. This keeps relativelocations of the adjacent heat exchanger cores from shifting in theproduction of the flat-tube heat exchanger.

REFERENCE SIGNS LIST

1 hairpin tube 2 fin 2 a core 2 b brazing material 3 fin assembly 4coupling element 5 header 6 distributor 7 brazing sheet 7 a core 7 bbrazing material 8 fin collar 9 spacer block 10 heat exchanger core 11heat exchanger core 12 heat exchanger core 15 flat tube 20 sheetmaterial 30 anti-joining sheet 51 upper front panel 52 lower front panel53 left side panel 54 fan guard 55 air outlet 56 base panel 57compressor 58 accumulator 59 air inlet 100 flat-tube heat exchanger 101flat-tube heat exchanger 107 flat-tube heat exchanger 108 flat-tube heatexchanger 109 flat-tube heat exchanger 111 heat exchanger core

-   -   112 heat exchanger core 122 heat exchanger core 200 outdoor unit        211 fin 212 fin 221 fin 222 fin 231 fin 232 fin    -   241 fin 242 fin 251 fin 252 fin 261 fin 262 fin    -   271 fin 272 fin 281 heat exchanger core 282 heat exchanger core        291 heat exchanger core 292 heat exchanger core 311 heat        exchanger core 312 heat exchanger core 411 heat exchanger core    -   412 heat exchanger core 511 heat exchanger core 512 heat        exchanger core 611 heat exchanger core 612 heat exchanger core    -   711 heat exchanger core 712 heat exchanger core

1. A heat exchanger comprising a plurality of heat exchanger cores, eachof the plurality of heat exchanger cores including a plurality oftabular fins with notches formed therein and a plurality of heattransfer tubes, wherein: the fins are disposed such that planes of thefins face each other and the heat transfer tubes are placed in thenotches in the fins so as to extend in a direction crossing the planesof the fins; and the plurality of heat exchanger cores are placed sideby side in a direction crossing a direction in which the notches arearranged along the fins and extending along the planes of the fins, andadjacent ones of the heat exchanger cores are brazed together. 2.(canceled)
 3. The heat exchanger of claim 1, further comprising abrazing sheet placed between the adjacent ones of the heat exchangercores, wherein the adjacent ones of the heat exchanger cores are brazedtogether by the brazing sheet.
 4. The heat exchanger of claim 3, whereinat least either of the fins or the brazing sheet includes a brazingmaterial.
 5. The heat exchanger of claim 1, wherein the fins include acore and the brazing material.
 6. The heat exchanger of claim 1,wherein, in the fins in at least one of the adjacent ones of the heatexchanger cores, end faces of the fins facing of the an other of theadjacent ones of the heat exchanger cores are bent.
 7. The heatexchanger of claim 1, wherein, in the fins in at least one of theadjacent ones of the heat exchanger cores, the heat transfer tubes areexposed on end faces facing an other of the adjacent ones of the heatexchanger cores.
 8. The heat exchanger of claim 7, wherein a blockelement made of metal is disposed between the adjacent ones of the heatexchanger cores and the adjacent ones of the heat exchanger cores arejoined together via the block element.
 9. The heat exchanger of claim 1,wherein the plurality of heat transfer tubes are hairpin tubes each ofwhich is bent in a U-shape, and in one of the hairpin tubes, one of apair of straight-tube portions extending in a lateral direction of theheat exchanger is located on an end face, of one of the adjacent ones ofthe heat exchanger cores, facing an other of the heat exchanger coresand an other of the pair of straight-tube portions is located on an endface, of the other of the heat exchanger cores, facing the one of theheat exchanger cores.
 10. The heat exchanger of claim 1, wherein theplurality of heat transfer tubes are coupled together at one end by aheader and coupled together at an other end by another header.
 11. Anair-conditioning apparatus equipped with the heat exchanger of claim 1.12. A method for producing a heat exchanger that comprises a pluralityof heat exchanger cores, each of the plurality of heat exchanger coresincluding a plurality of tabular fins with notches formed therein and aplurality of heat transfer tubes, the method comprising: forming theheat exchanger cores in which the fins are disposed such that planes ofthe fins are opposed to each other and that the heat transfer tubes areplaced in the notches in the fins so as to extend in a directioncrossing the planes of the fins; placing the plurality of heat exchangercores side by side in a direction crossing a direction in which thenotches are arranged along the fins and extending along the planes ofthe notches; and joining together adjacent ones of the heat exchangercores by brazing.
 13. (canceled)
 14. The method of claim 12, wherein abrazing sheet is used for brazing.
 15. The method of claim 14, whereinthe brazing sheet is made up of only a brazing material.